Tuesday is the busiest primary night of 2014, with voters heading to the polls in Alabama, California, Mississippi, Iowa, New Jersey, Montana, New Mexico and South Dakota.

It's a big night, with the tea party's last chance to save face in the Mississippi Republican Senate primary, a close contest in Iowa's Republican Senate primary , plus highly competitive House races in California, New Jersey, Iowa and Alabama.

After the polls close, Roll Call's Politics Team will have a live blog of the results. In the meantime, here are seven things to watch in Tuesday's primaries:

1. Does the tea party get its last big win of the cycle? The tea party and outside conservative groups have put their full force behind state Sen. Chris McDaniel, spending millions of dollars to help him oust Sen. Thad Cochran, R-Miss. This race has come to epitomize the fracture between the tea party and the establishment, and recent polling has found it coming to a close finish. In the final weeks of the campaign, the arrest of two McDaniel supporters — for allegedly photographing Cochran's bedridden wife at her nursing home — has overshadowed other issues in the race.

2. In Iowa, will state Sen. Joni Ernst win the GOP nomination outright? Ernst is the front-runner in the battle for the Republican nomination in Iowa, but she needs 35 percent of the primary vote to win the nomination and avoid an unpredictable convention fight. The most recent public poll had Ernst just breaking that threshold, at 36 percent.

Iowa's first open Senate seat in three decades has drawn a crowded field of Republicans, including former energy executive Mark Jacobs, talk radio host Sam Clovis, and former District Attorney Matt Whitaker. If the primary goes to convention, approximately 2,000 delegates will decide the nominee, and anyone can be nominated — including someone who was not on the primary ballot. Ernst would likely have an edge in a convention, but Clovis would be one to watch. The winner takes on the presumptive Democratic nominee, Rep. Bruce Braley, in this competitive Senate race.

3. Will comeback bids prevail in Mississippi and California? Two former members are looking for redemption in 2014 — but this time they're attempting to come back to Congress without their respective party's support.

In California's 31st District, Democrats have panned former Rep. Joe Baca’s bid to return to Capitol Hill. Party operatives worry he could be a spoiler in a coveted House seat the party floundered in 2012 . Democratic operatives fear Baca's familiarity with voters from his time in Congress will peel support from the other top two Democratic candidates, but won't be enough to earn him a spot in the general election. In the Golden State's top-two primary system, that could allow for two Republicans to squeak through — a repeat of what happened to Democrats last cycle in this otherwise favorable district for the party.

In Mississippi, former Rep. Gene Taylor is making a comeback bid — as a Republican — after representing the region for 21 years as a Democrat. Taylor is looking to oust Republican Rep. Steven M. Palazzo, who defeated Taylor in the 2010 GOP wave. Angered by the move, some Republicans in Mississippi’s 4th District sought to have him removed from the ballot. However the state party ruled to allow his bid, which GOP operatives say is a long shot.

4. Will national Republicans' favored candidates win in California, Iowa and New Jersey? A trio of GOP candidates could take competitive seats off the map for Republicans if they win the nomination Tuesday. In California, GOP operatives say former Capitol Hill aide Igor Birman would be the least-desirable Republican to face freshman Rep. Ami Bera, D-Calif., in the 7th District. They prefer former Rep. Doug Ose, R-Calif., win the nod.

In Iowa’s highly-competitive 3rd District, national Republicans warn the GOP front-runner, state Sen. Brad Zaun, would not play well against the de facto Democratic nominee, former state Sen. Staci Appel. Republicans expect their nominee to be decided at a convention, which, like the Senate race, is triggered when no candidate surpasses a 35-percent threshold. This is the race to replace retiring GOP Rep. Tom Latham.

And in New Jersey, frequent candidate Steve Lonegan, a tea party favorite, is giving Republican operatives a heart attack with his bid to succeed retiring GOP Rep. Jon Runyan. The 3rd District is competitive, and Lonegan’s fiery persona could imperil the party’s chances of keeping the seat if he wins the nomination. GOP operatives said they are increasingly confident their preferred nominee, Randolph Township Mayor Tom MacArthur, is expected to win. 5. Which Democrat(s) win the primary in Hollywood's House seat? Several A-list celebrities have gotten involved financially in the open 33rd District contest based in the wealthy areas of Beverly Hills, Santa Monica and Hollywood. Rep. Henry A. Waxman, D-Calif., is retiring, leaving a wide-open race for his seat.

Under the state's top-two primary, it's possible for two Democratic candidates to advance to the general election in this strong Democratic district — most likely state Sen. Ted Lieu and former Los Angeles Controller Wendy Greuel. That would drag out this already expensive House race through the fall.

But if the crowded Democratic field splinters the vote, attorney Elan Carr, the only Republican on the ballot, could grab one of the two general election slots. A Republican versus Democrat race could effectively end the contest in this district, which Obama carried by a 24-point margin in 2012.

6. Which Democrats will finish second in California? Golden State operatives predict embarrassingly low turnout Tuesday — especially among Democrats. With most of the primary action on the GOP's side , more Republicans are expected to turn out in the statewide primary. That means some Democrats, including members, could come in second place in the "top two" primary. Accordingly, Democratic operatives warn not to make sweeping conclusions if Democrats garner lower-than-expected vote counts.

7. Who are the next members of Congress who win primaries in safe seats? Three open-seat primaries in strong GOP and Democratic districts are likely to determine the newest members of the 114th Congress. In New Jersey’s 12th District, a crowded Democratic field to replace retiring Rep. Rush D. Holt has come down to two contenders : state Assemblywoman Bonnie Watson Coleman and state Sen. Linda Greenstein. The victor will come to Congress, in all likelihood.

And in Iowa, Rep. Bruce Braley’s Senate bid opened up his 1st District — another safe seat for Democrats. State Rep. Pat Murphy, the former speaker of the state House, is the front-runner among a five-candidate Democratic field.

Finally, in Alabama’s 6th District, state Rep. Paul DeMarco is the front-runner in the open-seat race to replace retiring GOP Rep. Spencer Bachus. The race is expected to continue in a runoff — which occurs when no candidate gets a majority of the vote — with one of three candidates: surgeon Chad Mathis, businessman Will Brooke or state Sen. Scott Beason.